An active agent or drug (e.g., pharmaceuticals, vaccines, hormones, nutrients, etc.) may be administered to a patient through various means. For example, a drug may be ingested, inhaled, injected, delivered intravenously, etc. In some applications, a drug may be administered transdermally. In some transdermal applications, such as transdermal nicotine or birth control patches, a drug is absorbed through the skin. Passive transdermal patches often include an absorbent layer or membrane that is placed on the outer layer of the skin. The membrane typically contains a dose of a drug that is allowed to be absorbed through the skin to deliver the substance to the patient. Typically, only drugs that are readily absorbed through the outer layer of the skin may be delivered with such devices.
Other drug delivery devices are configured to provide for increased skin permeability to the delivered drugs. For example, some devices use a structure, such as one or more microneedles, to facilitate transfer of the drug into the skin. Solid microneedles may be coated with a dry drug substance. The puncture of the skin by the solid microneedles increases permeability of the skin allowing for absorption of the drug substance. Hollow microneedles may be used to provide a fluid channel for drug delivery below the outer layer of the skin.
The invention provides such a drug delivery device. These and other advantages of the invention, as well as additional inventive features, will be apparent from the description of the invention provided herein.